Current mass-produced transformers are generally made by winding insulated wire around a bobbin, with a hollow core. The bobbin is generally nonconductive and is a spool that allows the winding of different sized wire in the center of the bobbin/spool. This bobbin is similar to bobbins used on a sewing machine.
One wire size is wound around until the number of needed turns is made for the first wire generally called the primary. The ends are brought out so they can be mounted on a firm base later on. Next another winding, called a secondary is wound on top of the primary winding or sometimes on a second bobbin. When enough wire turns are wound the spool is complete and the wires for the secondary winding are mounted for easy attachment. The primary windings are for the incoming AC voltage and the secondary is for the output AC voltage. In general the ratio of the primary to the secondary windings determines the increase or decrease in AC voltage in the transformer.
When the windings on the bobbin are completed, it is desirable to have a continuous core that surrounds the windings and passes through the center hole in the bobbin. This is normally accomplished by forming pieces of flat metal cut so that layers of the core material can be laminated around the windings, making a jigsaw like pattern held together physically or with glue. The wire mountings are then labeled.
This is a general method for mass producing transformers, requiring multiple steps, some of which require hand assembly. The process must be closely controlled to insure desired results and there are many places where the windings can be broken, the number of windings can vary, and/or the placement of the wires will vary slightly. The wire insulation must not be damaged and other manufacturing techniques must be exact to achieve the desired results.
Power distribution systems usually require miles of cabling, transformers mounted on stationary or movable platforms, and various other electrical equipment systems. The power transformer is required to reduce voltage levels from high transmission levels to usable lower levels. For example, power distribution systems for coal and other horizontal mines are required to provide electricity for mining machines, lighting, ventilation, safety, transportation, and other needs.
Current transformers used in the mines are virtually identical in form and function to those used in commercial power grids. These transformers are of various types, but typically they consist of wire wound around a metal or magnetic susceptible core. A large number of windings on the primary input coil are used to induce a lower voltage using fewer windings in a secondary output coil. This reduction in voltage typically is accompanied by a power loss in the form of heat. The heat is normally dissipated by using a cooling fluid around the core/windings.
Heat is the ruin of transformers because of lost power, degradation of the wiring insulation, and reduction in the life and performance of the transformer. The fluid cooling systems on the transformer add significantly to its weight and size, making the transformer bulky, difficult to handle especially in underground applications. Further, the cooling fluids can overheat causing rupture of the cooling vessels. The loss of the cooling fluids quickly hastens failure of insulation, causing transformer failure and possible fire. Constant maintenance on the transformer systems is needed making the cost of operating the transformers expensive. What is needed are smaller transformers that have high efficiency cores and thick insulation that can tolerate higher temperatures and that can work over a much higher temperature range and with much fewer failures when overloaded, compared to existing transformers.
Printed circuit boards provide good insulation and have circuit traces in combination with vias. U.S. Patent Application No. 20060109071 discloses a three-layered printed circuit board having one top layer, one middle layer, and one bottom layer with circuit traces on the top and bottom layers. The top and bottom layers are laminated to the middle layer which contains an amorphous metal or other magnetically susceptible core therein. Traces on the top layer, traces on the bottom layer, and conductive vias through all the layers form a single coil around the core. A current through the coil creates a magnetic field in the core, which can be used to couple one or more signals together through magnetic flux. To increase the level of the signal, more windings would be required, since the magnetic field strength is proportional to the number of windings around the core. In the Motorola design, the coil is limited to a single layer, so a larger number of windings (turns) in a coil would have to be physically spread out over a large area rather than lying on top of each other as in a transformer. Spreading the coil over a large area would limit the magnetic flux that can be generated in the core. To add more windings the core would have to be extended, which reduces the magnetic field in any cross-section of the core for any specific signal, voltage or current.
In typical transformer designs, multiple windings are laid concentrically with sufficient turns so that the required magnetic flux is obtained in the core. Having only a single layer of windings greatly limits the amount of magnetic flux that can be induced in a core. The magnetic field generated by the primary windings surrounding the core transfer energy to the secondary windings with high efficiency. The ratio of the number of input windings to the output windings, called the turns ratio, determines the voltage change and current availability at the output. The product of the current and voltage at the input and output are identical for an ideal transformer. With proper selection of the turns ratio, voltage levels can be increased at the expense of current, or current levels can be increased at the expense of voltage. Total energy is always conserved between the input and output windings.
The design in U.S. Patent Application No. 20060109071 is severely limited in the number of turns that can be made around the core for any given distance of core. As a result this design cannot be used to generate a magnetic field for attracting, repelling, or inducing magnetic fields to perform work. This design, having only a single layer of windings on a core, cannot provide the power needed for such devices as transformers and the like. With regard to using a circuit board design for a transformer, what is needed is a design that will allow multiple windings laid concentrically with sufficient turns so that the required magnetic flux is obtained in the core to produce useful power transfer.